The non-pregnant uterus shows wave-like activity throughout the menstrual cycle. This uterine activity was ®rst detected using intra-uterine pressure recordings. The use of ultrasound has made it possible to study the movements of the uterus in a non-invasive manner. Throughout the menstrual cycle, several wavelike activity patterns have been described; these patterns change throughout the menstrual cycle and are governed by steroid hormones. An adequate wave pattern seems to be related to

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... ssful reproduction in spontaneous cycles and assisted reproduction. Further insight into the phenomenon of endometrial wave-like activity might offer an opportunity to correct abnormal wave patterns and thereby improve pregnancy rates.